Prior control handles are typically implemented with pneumatic, mechanical, or electrical hardware. In high reliability applications, such as for brake systems for locomotives, the control handles are almost entirely implemented with pneumatic or mechanical linkages. Control handles implemented with electrical hardware are disclosed in two published patent applications, incorporated here by reference, numbered 20040168606 and 20040168539. The control handles disclosed in those applications are superior to previous handles because they are smaller, easier to maintain, and more reliable.
Spiral sensors are a type of non-contact robust position sensor that is disclosed in U.S. Pat. No. 5,815,091, also incorporated by reference. In essence, a spiral sensor consists of 2 parts, one that moves in relation to the other. The output of the sensor is a measurement of the relative displacement between the two parts. Applications 20040168606 and 20040168539 disclose, but do not claim, using Spiral Sensors in a control handle. Applications 20040168606 and 20040168539 also disclose a control handle wherein contact switches are used to detect handle position. However, they do not disclose a control handle in which both contact switches and a Spiral sensor are used. Furthermore, they do not disclose a control handle wherein electrical switching elements and Spiral sensor elements are combined on the same printed circuit board.
The present invention combines electrical switches and Spiral sensing to overcome limitations in the prior art.